Maybe make a sig so we can see what youur system is. i7s really shine in SLI situations, so if you have 295 SLI, then it would probably be a pretty decent upgrade. For a single 295, maybe not so much - depends on what games you are talking about.
You could always overclock the Q6600. Not sure how high you will be able to go on that 680i board, but going from 2.4Ghz to 3.2Ghz+ will give you a nice increase in speed.